The goals of our research are to understand the molecular basis for the tissue specific control of gene expression. To accomplish these goals we are studying the origin and expression of a duplication of the Adh locus in D. mojavensis and other related species. We are specifically focusing on several changes in gene expression which have evolved since the origin of the duplication. The first of these is the expression of Adh-1 in the ovary of D. mojavensis and D. arizonensis. We will compare the nucleotide sequence of the Adh locus in these two species with their two closest relatives, D. mulleri and "species N", that do not express Adh-1 in the ovary. We will identify potential regions of the DNA which could be relevant to ovary expression and test their functional role using P element mediated transformation. We will extend our studies on Adh-1 regulation to characterize the polymorphism of Adh-1 expression in regions of the larval gut. Lines will be constructed which breed true for alternate patterns of gut Adh-1 expression and the correlation which appears to exist between gut expression and restriction fragments which include the 5' region of the Adh-1 gene will be studied in a genetic analysis. We will extend our studies to the origin of the Adh duplication and alternate expression patterns to other species in which we have already documented patterns of Adh expression which are different from the usual pattern of expression found in species with two Adh genes. These analyses will also contribute to our knowledge about the origin of the duplication. Additional experiments aimed at understanding the origin of the duplication will be conducted. Finally we are interested in providing information related to the hypothesis that major events of evolution are changes in regulatory information. To accomplish this, experiments will be conducted to determine if any of the altered patterns of Adh-1 expression that have been observed i.e. ovary expression or gut expression, can be associated with an adaptively significant function.